It occurred to me that Martijn van Buul wrote in gmane.os.netbsd.devel.network:

[ problems with my ral-based AP ]

> Is this a known problem? Is there anything I can do to assist solving it?

I located the culprit: It was a hardware problem afterall, and one of the
nasty kind.

Apperently, the PCI ral card I bought (an E-tech WGPI03) is a horrible
abobination, as it's actually a mini-PCI card on a passive converter
slot - of course covered by a nice metal shield, so noone sees how 
horrible it really is. I wouldn't be overly surprised if this breaks
several aspects of the PCI standard, and apperently the motherboard of my
router didn't really appreciate it that much, making the card reset itself
under traffic. When I tested it, I did so on a different machine - apperently
one which is a bit more tolerant about all this, so I out-ruled the 
possibility that the card was broken. It obviously worked on a different
machine, right? 

Well, no.

Replacing the E-tech card with a different one (A sitecom, this time - 
Same price range, same chipset...) solved the problem. 

Sorry for the noise.
-- 
    Martijn van Buul - pino@dohd.org - http://www.stack.nl/~martijnb/
	 Geek code: G--  - Visit OuterSpace: mud.stack.nl 3333
 The most exciting phrase to hear in science, the one that heralds new
discoveries, is not 'Eureka!' (I found it!) but 'That's funny ...' Isaac Asimov